Problem: Rewrite ${\dfrac{4^{-9}}{4^{-5}}}$ in the form ${4^n}$.
${ \dfrac{4^{-9}}{4^{-5}} = 4^{-9-(-5)}} $ ${ \hphantom{\dfrac{4^{-9}}{4^{-5}}} = 4^{-4}} $